Jeff Lilly: Free-running sleep, in my mind, is fairly simple: you go to bed when you're tired, regardless of the hour of day, and wake up without an alarm (this is what I'm doing for my current three-day "reboot" between polyphasic sleep and biphasic sleep). I can think of a couple variations: for one, you could go to sleep at a set time but wake up without an alarm--this would allow a fair measure of consistency in your sleep and wake patterns. Another is described in
this article, though it seems to treat free-running sleep less as a long-term lifestyle choice and more as a tool for discovering the workings of your personal circadian rhythm. I admit I haven't read the whole article, but from what I have read it looks like it could be helpful.